Currently, in the field of wastewater treatment, submersible mixers are widely utilized in both China and most of other countries for industrialized-scale treatment of liquid mixture. The blades designed for these submersible mixers are all made of rigid material. As drive motors of these submersible mixers were installed below the liquid surface, the designing and manufacturing processes of these mixers require sophisticated techniques. Besides, once being manufactured out, these mixers are usually considerably huge. As to those experimental-use small mixers, like those designed out of the same principles for industrialized production, they also present a variety of shortcomings such as inconvenience for being placed in the channel of a biopool, inducing undesirable flow states, high manufacturing cost, vulnerability to damage and difficulty for maintenance. Therefore, they are not suitable for being used in the wastewater treatment that requires long operational duration and high stability.
With increasing demand in municipal sewage treatment and increasingly strict standards on effluent discharge, more and more efforts, financially and scientifically, have been taken to realize up-standard discharge of municipal sewage. Therefore, the research and development of small-sized, high-efficient devices for wastewater treatment are of great market potential.
Chinese Patent CN 2031551410 (date of authorization: 2013 Aug. 28) disclosed a blade device used on a precipitated-silica pulping machine. The blade device comprises two mutually symmetric components that are bolted on the main shaft via a connecting plate. Each component bears two identical blade units that are 90-degree connected to each other through a base plate, and four blade units of the two components constitute the whole blade-containing mixing system. Each blade unit consists of a horizontal blade and a vertical blade, and both the horizontal and vertical blades are in serrated form. When being adopted for pulping precipitated silica, this blade device presents some advantages such as good shearing effect, short pulping time and low energy consumption. However, it has some disadvantages as well. For example, both horizontal and vertical blades of the blade device are installed at fixed places and are made of rigid material, which make the whole blade device, apart from desirable shearing force and mixing effect, generates no forward-going and uplifting force. Therefore, the blade device disclosed in this cited invention shows poor effect in propelling the liquid mixture upward.